Towards clinical adherence monitoring of oral endocrine breast cancer therapies by LC-HRMS-method development, validation, comparison of four sample matrices, and proof of concept

An LC-MS/MS method for tamoxifen and six metabolites in VAMS was developed and validated, with water prerinsing improving recoveries and poor room temperature stability but stability for at least 100 days at minus 80 degrees Celsius. Plasma to blood ratios were used to estimate plasma equivalent concentrations, and paired VAMS and plasma samples from ten breast cancer patients showed strong correlations and good agreement on Bland-Altman analysis, supporting reliable decentralised TDM.

Development and validation of an LC-MS/MS method for the comprehensive quantification of tamoxifen and its metabolites in volumetric absorptive microsampling: clinical application in breast cancer patients — Kuo et al., Analytical and bioanalytical chemistry (paywalled) · source ↗

• blood
• dried
• vams
• neoteryx-mitra
• validation
• venous-agreement
• tdm
• oncology

The study developed and validated a reliable HPLC-MS method for quantifying multiple tyrosine kinase inhibitors from VAMS microsamples of capillary blood, showing acceptable accuracy, precision, and 28-day stability at -21°C, with results comparable to venous plasma in 194 samples from patients with solid tumours. This enables therapeutic drug monitoring using microsamples in oncology practice.

HPLC-MS Quantification of Multiple Tyrosine Kinase Inhibitors in Patients with Solid Tumors: Method Validation and Clinical Application — Staudinger et al., Pharmaceutics (paywalled) · source ↗

• blood
• dried
• capillary
• vams
• neoteryx-mitra
• validation
• tdm
• oncology

Dried saliva collected with the Mitra device correlated strongly with wet saliva but poorly with plasma unbound and total concentrations, indicating it is not a reliable substitute for plasma in routine therapeutic drug monitoring of mycophenolic acid and its glucuronide metabolite. Capillary blood collected via VAMS remains a promising alternative for long term monitoring in paediatric patients.

Volumetric Absorptive Microsampling of Saliva for Pharmacokinetic Evaluation of Mycophenolic Acid and Its Glucuronide Metabolite in Pediatric Renal Transplant Recipients: Bioanalytical Method Validation and Clinical Feasibility Evaluation — Kocur et al., Pharmaceuticals · source ↗

• blood
• saliva
• dried
• capillary
• vams
• neoteryx-mitra
• validation
• pediatric
• tdm
• immunosuppressants

Microsampling with Mitra® devices correlated strongly with venous plasma for capecitabine therapeutic drug monitoring (r=0.97), but yielded consistently lower concentrations. Patients preferred this method and reported minimal pain, suggesting it is suitable for patient-centric oncology drug monitoring in decentralised settings.

Comparison of capecitabine concentrations determined by microsampling versus plasma concentrations for therapeutic drug monitoring: a pilot study — Shafiei et al., The Journal of pharmacy and pharmacology (paywalled) · source ↗

• blood
• dried
• capillary
• vams
• neoteryx-mitra
• validation
• venous-agreement
• acceptability
• tdm
• oncology

An on-line SPE-LC-MS method using 10 microlitre capillary blood samples collected on VAMS tips achieved lower limits of quantitation of 0.03 micromolar for methotrexate and 7-OH-MTX and 0.05 micromolar for DAMPA, with acceptable accuracy and precision. A plasma-to-whole-blood correlation factor of 0.46 was observed, supporting low-volume pediatric drug monitoring.

Development and validation of a bioanalytical method for the quantification of methotrexate from serum and capillary blood using volumetric absorptive microsampling (VAMS) and on-line solid phase extraction (SPE) LC-MS — Opitz et al., Journal of chromatography. A (paywalled) · source ↗

• blood
• dried
• capillary
• vams
• neoteryx-mitra
• validation
• pediatric
• tdm
• oncology